Selaginella

Some plants can come back to life.

They curl up into brown balls when it is dry. This helps them stay safe. When they get water, they turn green and grow again.

These plants are called spikemosses. There are over 750 kinds of them. Most live in warm, tropical lands. Some live in very cold places, too.

Some even have shiny colors that glow. These plants are very special.

Spikemosses are a large group of plants. There are over 750 known species. Most live in warm, tropical areas. Some live in very cold places.

These plants have small, scale-like leaves. We call these leaves microphylls. They grow on branching stems. Some species can survive without much water. This is called poikilohydry. When it is dry, they curl into brown balls.

When they get water, they turn green again. People call these resurrection plants.

Some spikemosses love the shade. They have special parts called chloroplasts. These parts use light to make food. In many species, there is only one giant chloroplast in each cell. This helps them live in low light.

Other species live in bright light. They have many small chloroplasts instead. Some species even have shiny, glowing colors.

Selaginella is a large group of plants known as spikemosses. There are over 750 known species in this group. Most of these plants live in warm, tropical regions. However, a few species live in very cold, arctic-alpine zones. They are often called fern allies because they are related to ferns. These plants are very old and have been around for a long time. Fossils show they have existed for over 300 million years.

These plants have a very interesting way of growing. They have branching stems with small, scale-like leaves called microphylls. Some stems grow along the ground, while others stand up straight. Inside the stems, they have special tube-like structures called trabeculae. These connect the stem's center to the outer layers. Most species have two different types of spores. These are called megaspores and microspores.

Scientists have studied these plants to learn how they work. A species called Selaginella moellendorffii is a very important model organism. This means scientists use it to study how life works. The United States Department of Energy's Joint Genome Institute has even sequenced its genome. This is the complete set of instructions for the plant. In the past, a man named Palisot de Beauvois named the genus. He first named it for the species Selaginella selaginoides.

Some species have amazing ways to survive dry weather. This ability is called poikilohydry. Some plants, like Selaginella bryopteris, are called resurrection plants. When it is dry, they curl into brown or reddish balls. They can even be uprooted in this state. Once they get water again, they turn green and start growing. About 70% of species have one giant chloroplast in their cells. This helps them live in very low light.

Many people like to grow these plants at home. Tropical species are very popular for cultivation. You might find Selaginella kraussiana, also called golden clubmoss, in a shop. Another beautiful one is Selaginella willdenowii, which has iridescent colors. This means it can look shiny or glowing in the light.

These plants show us how life can adapt to many different places on Earth.

Selaginella is a diverse genus of lycophytes commonly known as spikemosses or lesser clubmosses. This group contains over 750 known species that play important roles in various ecosystems. While they are often called "fern allies," they are actually a distinct group of vascular plants. They are found mostly in tropical regions across the world. However, a few species inhabit the cold arctic-alpine zones of both hemispheres. These plants are incredibly ancient, with fossils dating back over 300 million years to the Late Carboniferous period.

The physical structure of Selaginella is quite specialized. These plants feature branching stems that may creep horizontally along the ground or grow in an upright position. Their leaves are small and scale-like, which scientists call microphylls. In most lycopods, these leaves have a single unbranched vein, but some Selaginella species possess a branched vascular trace. Inside the stems, the vascular system consists of polystelic protosteles. This means the stem section shows more than two protosteles. Each stele is made of diarch xylem and exarch xylem, which grows outward. These steles connect to the cortex through tube-like structures called trabeculae. These trabeculae are modified endodermal cells that feature casparian strips on their lateral walls.

Reproduction in Selaginella relies on a process called heterospory. This means the plants produce two different sizes of spores: megaspores and microspores. In certain species, such as Selaginella rupestris, fertilization occurs while the megaspore is still attached to the parent plant. The spore is only released once the embryo has already produced its root and cotyledons. This method ensures the young plant has a head start in its environment. This complex reproductive cycle is a key feature that distinguishes them from many other plant groups.

One of the most remarkable traits in this genus is poikilohydry. This is the ability to survive extreme dehydration. Under very dry conditions, some species can roll up into tight, brown or reddish balls. In this dormant state, they can even be uprooted from the soil. When moisture returns, they rehydrate, turn green, and resume growth. Plants like Selaginella bryopteris are famously called resurrection plants because of this ability. This survival mechanism is linked to tandem gene duplications, which help the plants tolerate desiccation. This is different from the whole genome duplication seen in other evolutionary histories.

Selaginella species have also evolved unique ways to manage light through their chloroplasts. Chloroplasts are the parts of a cell that handle photosynthesis. About 70% of Selaginella species are monoplastidic, meaning they have one single, giant chloroplast per cell. This is a specialized adaptation for living in very low-light conditions. These monoplastidic species receive only 0.4% to 2.1% of full sunlight. In contrast, species with multiple chloroplasts per cell live in open areas. These species receive an average of more than 40.5% of full sunlight. This shows how the genus has adapted to many different light levels.

The taxonomy, or scientific naming, of Selaginella has a long and complex history. The name was first established by Palisot de Beauvois for the species Selaginella selaginoides. Over time, many scientists have attempted to divide the genus into different groups. For example, some researchers suggest using names like Bryodesma or Lycopodioides to separate certain species. In 2004, a study by Korall and Kenrick used DNA sequences to show that the Euselaginella group is very ancient. This group includes the type species and a Hawaiian species called Selaginella deflexa. More recently, in 2023, scientists Zhou and Zhang suggested the genus could be broken into 19 different genera.

Today, Selaginella remains a subject of great scientific interest. The species Selaginella moellendorffii serves as an important model organism for researchers. Its entire genome has been sequenced by the Joint Genome Institute of the United States Department of Energy. This allows scientists to study the fundamental mechanics of plant life. Many species are also popular in cultivation due to their beauty. You might find Selaginella kraussiana, known as golden clubmoss, or the iridescent Selaginella willdenowii in many collections. These plants continue to provide deep insights into how life adapts to a changing world.